package com.favorite;

public class Solution116 {
    public Node connect(Node root) {
        connectNode(root);
        return root;
    }

    public void connectNode(Node node) {
        if (node == null) return;
        if (node.left != null) {
            node.left.next = node.right;
        }
        if (node.next != null) {
            if (node.right != null) {
                node.right.next = node.next.left;
            }
        }
        connectNode(node.left);
        connectNode(node.right);
    }
}

class Node {
    public int val;
    public Node left;
    public Node right;
    public Node next;

    public Node() {
    }

    public Node(int _val) {
        val = _val;
    }

    public Node(int _val, Node _left, Node _right, Node _next) {
        val = _val;
        left = _left;
        right = _right;
        next = _next;
    }
};

